<HTML><HEAD><TITLE>ColgenInstance:get(++What, -Value)</TITLE>
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<H1>ColgenInstance:get(++What, -Value)</H1>
Obtain global problem information.
<DL>
<DT><EM>What</EM></DT>
<DD>Specification for information wanted (atom)
</DD>
<DT><EM>Value</EM></DT>
<DD>Returned value of What
</DD>
</DL>
<H2>Description</H2>
<P>
   Retrieve information about solver constraints and results, for the
   colgen instance ColgenInstance. What can take one of the following values:

<DL>
    <DT><TT>dual(+Id)</TT>
      <DD>Returns the floating-point value of the
      current dual value for the constraint having identifier Id. See
      also <TT>sp_obj</TT> below.
<P>
    <DT><TT>sp_obj(+Id)</TT>
      <DD>Returns the sub problem objective terms currently associated
      associated with the constraint having identifier Id. This will
      be a term <TT>Val*Var</TT> where Val is the current dual value
      for the constraint as also returned by
      <TT>ColgenInstance:get(dual(Id), Val)</TT> and Var is the
      subproblem variable in the implicit sum term of the
      constraint. It is the users responsibility to get all relevant
      terms of the current cost function and ensure that subproblem
      solutions posted to the colgen instance have a non-negative
      cost.
<P>
    <DT><TT>vars</TT>
      <DD>Returns a list of all variables currently
      associated with the colgen instance <TT>ColgenInstance</TT>.
<P>
    <DT><TT>non_zero_vars</TT>
      <DD>Returns a list of all variables currently associated with
      the colgen instance <TT>ColgenInstance</TT> that have a non-zero
      optimal solution. This may be more efficient than retrieving all
      problem variables after solution, since very many variables can
      be generated and most will have a zero value in the optimal
      solution.
<P>
    <DT><TT>frac_vars</TT>
      <DD>Returns a list of all variables currently associated with
      the colgen instance <TT>ColgenInstance</TT> that have a
      fractional optimal solution. This is intended for use primarily
      in user-defined problem branching predicates.
</DL>

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